Just returned from Philadelphia where I had my first ever business class flight with BA on 747 upper deck. Sadly my return was in economy, but I enjoyed it nonetheless.
I flew out on December 27 and it was very quiet - there were no more than 10 of us upstairs and only 5 of us in business between Glasgow and London. Felt a bit annoyed after paying an extortionate amount to reserve my seat, but it was worth it to ensure I was upstairs I guess! I was sat in 64K which was as good as the reviews suggest. Very spacious and you don't have to climb over the person next to you (not that it mattered on this flight.) I even got an hour of rest in the flatbed which was novelty for me.
I thought the food was pretty average but still better than what you'd get in economy, but the crew were very attentive and more than happy to keep the beers coming.
If anyone else flies out business with BA, I'd highly recommend using the Terminal 5B lounge - it was much quieter than both 5A lounges and I thought it was a nicer area to sit in general. If you have enough time, I'd also recommend the complimentary Elemis spa! By contrast, the Glasgow lounge was nothing special. It was a nice place to relax before the flight, but I would've been just as happy sitting in the main terminal watching the apron.
The return flight was average but maybe it's because I was spoiled from the previous flight! I ended up stuck in a middle seat (my fault for not checking in) which was very cramped for 6′1" me - especially in comparison to the Emirates A380 I flew earlier this year. The crew were fine though.
All in all I felt quite spoiled! It's been by 7th or 8th 747 flight but likely to be my last for a while given that BA are replacing it with the A350 on the Philadelphia route.
For that reason, I asked the attendant for a cockpit trip which was a great experience! I took the attached photo when we landed in Philadelphia.